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UBV Photoelectric Photometry Catalogue
The UBV Photoelectric Photometry Catalogue, or UBV M, is the star brightness catalogue that complies to the UBV photometric system developed by astronomer Harold Johnson. Evolution of the UBV Photoelectric Photometry Catalogue The early edition of 1968 by Blanco, sometimes referred as simply the "Photoelectric Catalogue" or UBV was replaced by the Mermilliod edition UBV M in 1987 and extended in 1993. As the atmospheric extinction In astronomy, extinction is the absorption and scattering of electromagnetic radiation by dust and gas between an emitting astronomical object and the observer. Interstellar extinction was first documented as such in 1930 by Robert Julius Trum ... problem associated with the UBV photometric system became evident, the UBV Photoelectric Photometry Catalogue was phased-out in 2000. Download locations The UBV catalog data format is in plain text. After uncompressing by unzip or gunzip it can be seen by any text viewers or by the onlinADC viewe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
UBV Photometric System
The UBV photometric system (from ''Ultraviolet, Blue, Visual''), also called the Johnson system (or Johnson-Morgan system), is a photometric system usually employed for classifying stars according to their colors. It was the first standardized photometric system. The apparent magnitudes of stars in the system are often used to determine the color indices B-V and U-B, the difference between the B and V magnitudes and the U and B magnitudes respectively. The choice of colors on the blue end of the spectrum was assisted by the bias that photographic film has for those colors. It was introduced in the 1950s by American astronomers Harold Lester Johnson and William Wilson Morgan. A telescope and the telescope at McDonald Observatory were used to define the system. The filters are selected so that the mean wavelengths of response functions (at which magnitudes are measured to mean precision) are 364 nm for U, 442 nm for B, 540 nm for V. Zero points were calibrate ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Harold Johnson (astronomer)
Harold Lester Johnson (April 17, 1921 – April 2, 1980) was an American astronomer. Harold Johnson was born in Denver, Colorado, on April 17, 1921. He received his early education in Denver public schools and went to the University of Denver, graduating with a degree in mathematics in 1942. Johnson was recruited by the MIT Radiation Laboratory to work on World War II related radar research. After the war Johnson began graduate studies in astronomy at University of California, Berkeley where he completed his thesis under Harold Weaver in 1948. In the following years working at Lowell Observatory, University of Wisconsin–Madison, Yerkes Observatory (where he met William Wilson Morgan), McDonald Observatory, University of Texas–Austin, the Lunar and Planetary Laboratory in Tucson, Arizona, and the National Autonomous University of Mexico he applied his instrumental and electronic talents to developing and calibrating astronomical photoelectric detectors. He died of a he ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Extinction (astronomy)
In astronomy, extinction is the absorption and scattering of electromagnetic radiation by dust and gas between an emitting astronomical object and the observer. Interstellar extinction was first documented as such in 1930 by Robert Julius Trumpler. However, its effects had been noted in 1847 by Friedrich Georg Wilhelm von Struve, and its effect on the colors of stars had been observed by a number of individuals who did not connect it with the general presence of galactic dust. For stars that lie near the plane of the Milky Way and are within a few thousand parsecs of the Earth, extinction in the visual band of frequencies (photometric system) is roughly 1.8 magnitudes per kiloparsec. For Earth-bound observers, extinction arises both from the interstellar medium (ISM) and the Earth's atmosphere; it may also arise from circumstellar dust around an observed object. Strong extinction in earth's atmosphere of some wavelength regions (such as X-ray, ultraviolet, and infrared ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Unzip
ZIP is an archive file format that supports lossless data compression. A ZIP file may contain one or more files or directories that may have been compressed. The ZIP file format permits a number of compression algorithms, though DEFLATE is the most common. This format was originally created in 1989 and was first implemented in PKWARE, Inc.'s PKZIP utility, as a replacement for the previous ARC compression format by Thom Henderson. The ZIP format was then quickly supported by many software utilities other than PKZIP. Microsoft has included built-in ZIP support (under the name "compressed folders") in versions of Microsoft Windows since 1998 via the "Windows Plus!" addon for Windows 98. Native support was added as of the year 2000 in Windows ME. Apple has included built-in ZIP support in Mac OS X 10.3 (via BOMArchiveHelper, now Archive Utility) and later. Most free operating systems have built in support for ZIP in similar manners to Windows and Mac OS X. ZIP files gen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
